Electric discharge device



Oct. 9, 1934. [MAQKA 1,976,500

ELECTRIC DISCHARGE DEVICE Filed Feb. 28, 19:51

Inventor Yosh io Imaoka,

His Attorney.

Patented Oct. 9, 1934 ELECTRIC DISCHARGE, DEVICE Yoshio Imaoka, Tokyo,Japan, assignor to General Electric Company, a corporation of New YorkApplication February 28, 1931, Serial No. 519,159 In Japan March' 8,-1930' 2 Claims. (01. 250- 27.5)

with a control member for initiating the dis-' charge. A device of thistype is usually designated electrostatically controlled arc dischargeapparatus.

An object of the present invention is to provide a more accurate controlof the initiation of 0 the discharge in devices of this sort. A morespecific object is to improve the control member and to provide animproved position of the member with respect to the discharge device andcontained electrodes. These objects are attained in brief, by providinga control member external to the tube and which is adapted to be movedat will over the envelope, thereby to change its position with. respectto the electrodes, as will be explained hereinafter. A con- 0 trolmember of this sort is capable of accurately:

- external control member, also a different form of circuit, while Fig.3 shows a series of characteristics useful in explaining the electricalcontrol exercised by the movable control member. Referring to Fig. l,numeral 1 designates an evacuated envelope of vitreous materialcontaining an ionizable medium, for example, a fixed gas or vapor, at avpressure sufiicient to support an arc discharge at ordinary operatingvoltages. The gaseous medium may consist of neon, argon, nitrogen or thevapor of caesium or similar alkali metals, or of mercury at pressuresbetween a few microns to a few millimeters. The envelope terminates inoppositely directed reentrant stems 2, 3, the former of which supportsan anode 4 which conveniently may take the form of a graphite cylinder.A cathode 5 of any suitable and Well-known form, directly or indirectlyheated, is mounted on the stem 3. This cathode may be coated with anelectron-emitting substance such as alkaline earth material. External tothe envelope, there is a hollow metallic cylinder or ring 6 which fitsthe envelope rather loosely and is adapted to slide over the latter soas to approach toward or recede from either electrode; This ring isprovided with a bearing or slide 7 which is adapted to slide over'a rodguiding member 8 rigidly fixed in position. The force for moving thering electrode 6 may be exercised through a pulley and belt arrange- 50ment 9 as shown in Fig. 1, or the bearing '7 may contain screw threadswhich cooperate with a manually operated screw 10 as shown in Fig. 2.The electric discharge device is energized preferably through a voltagestep-up transformer 11 from a source of alternating Current energy, andthe output circuit includes a load 12, con-. veni'ently shown as arectangle. The voltage provided by the transformer ordinarily is justinsufiicient to initiate an arc discharge when the 0 ring 6 is in itsnormal position or is at a normal bias potential. This positionconveniently is midway between the electrodes. The load may constitute arelay or a multi-electrode tube connected in'cascade to the dischargedevice 1 or any other form .of load which respondsto current flowing insaid device. The cathode 5 may be energized by direct or alternatingcurrent, which source generically is indicated as an alternator 13connected to ground. One side I of the cathode is connected to one ofthe high voltage transformer terminals, and the other terminal of thetransformer is connected to the load as shown. The electrode or controlmember 6 is adjustably connected to the common .1.

nates of voltage at which a given are discharge 951 will start, andagainst an abscissa which indicates relative positions of the movablecontrol member along the envelope with respect to the electrodes. Itwill be noted that the starting voltage of the arc discharge is largestwhen the auxiliary electrode is nearly at its middle posi-' tion, i. e.half-way between the anode 4 and the cathode 5. In general, when thegrid voltage is negative with respect to the cathode, the value of thestarting voltage is higher, and vice versa'.

It is therefore evident from a consideration of these Curves that for agiven tube and grid biasing potential, the position of the controlmember determines the voltage at which the arc discharge will start tofiow between the eleci -QT rodes. The control member 6 thus ofiers aconvenient method of triggering the arc discharge in that it caneffectively control a change in output current which may be originallypresent simply as residual current, from a few microamperes to the fullload current of many amperes. This full load current is determined notonly by the conductivity of the tube which in turn is dependent upon thenature and pressure of gas and the spacing of electrodes but also uponthe requirements of the load'and the value of the applied voltage.scribed has many applications in the art, for example, it may be used asa self-levelling device for elevators in which it is conceivable thatthe control member 6 and its bearing 7 may be secured to an elevator sothat when the control member assumes a predetermined position on theenvelope due to the position taken by the elevvator, the arc dischargeis triggered and the load which conveniently may be a relay, serves;either to start or stop the elevator. Many other uses will occur tothose skilled inv the art.

In practice, the biasing battery 14provides a sufficiently negativepotential on the control member 6 that when the latter is in apredetermined position with respect to the inter-electrode space, whichconveniently is midway, the arc is restrained from flowing at the platevoltage employed. However, when the control member moves awayirom thismid-position and approaches one or the other of the electrodes, the arcis initiated as may be observed from the graph. 1 V p In addition tooffering a convenientmethodrof controlling an are by simply moving themember 6 over the envelope, the control member may also be employed foradjusting and calibrating the device for changes in ambient or operatingtemperatures 'which may alter the'voltage at which the arc will start.Obviously, the control A'device of the type der member may be moved to aposition on the envelope to permit the initiation of the are at any andall envelope temperatures which affect and determine the pressure of thegaseous contents. Furthermore, the control member may be moved to aposition such that the smallest change in anode voltage or in grid biaspotential is sufficient to start the arc. Thus in Fig. 2, the positionof the control member 6 is so regulated by the screw 10 that thesmallest potential applied to conductors 15 is sufficient to trigger thedevice. This potential may be derived, for example, irom a distantsignalling station in which case the device 1. operates as an electricalrelay which may actuatearelay load 12.

What I claim as'hew and desire to secure by Letters Patent of theUnitedStates is:

1. An electric discharge device comprising an envelope containing anionizable medium at a pressure sufi'icient to support, an arc dischargeatthe operating voltages, a cathode and a c0-' operating anode, meansforcontrolling the initiation of the arc, said means including a memberadapted to be electrically charged, movably mounted on the envelope andadapted to ap: proach one electrode and to recede from the otherelectrode whereby the voltage at which the arc is initiated is changed,

2. An electric discharge device comprising an,

envelope containing an ionizable medium. at a pressure sufficient tosupport an arc-like-dis charge at the operating voltages, acathode andcooperating anode and means for restraining the arc'discharge, saidmeans consisting of a control member which is adapted to move along theexterior of the-envelope between the cathode, and anode and means forcausing said control member to recede from one, electrode and approachtheother electrode whereby .the voltage at which the arc is initiated ischanged.

. ,YOSHIO IMAokA.

